Why isn't my iPhone working after the update?

Hello!
I have recently updated my iPhone 4 32 gb to iOS 7.1.2 and now it is useless. If someone had this problem please write what solved your problem.
In short terms:
After update iphone was stuck, I've tried hard reset (power button plus home button), this led me to - select your language, select your country - and than image appears connect to iTunes. I have tried at least 20 times connecting to iTunes to restore but my computer (Windows 7 x 64) doesn't recognize iphone so iTunes doesn't see it also. I updated iTunes and all drivers but no luck. I've tried 4 different apple usb cables but still nothing. On the other hand I have iPhone 3gs 32 gb and everything is fine. ITunes can recognize it, computer can see it in device manager and all usb cables work fine on 3GS,
I'm out of ideas, is there a way to fix this?

(I updated my iphone with the newest update, and now it just has the plug into itunes picture on the front,
I cannot charge it or plug into itunes for some reason)

1. Calm down and understand that you'll be fine.
2. Reboot your computer and then close any running app.
3. Make sure you've downloaded the latest iTunes version for your computer.
4. If the iPhone is still displaying the iTunes symbol and a cable, connect it to your computer via USB and then press and hold both the power and home buttons until the device powers off.
5. Now put the device in DFU mode. You can follow the simple instructions below.

Hold the power button for 3 seconds.

Now press and hold the home button while still pressing the power button for 10 seconds.

Release the power button only.

After about 8 seconds or so, you should get a prompt that iTunes has detected your iPhone in recovery, however, you will NOT see anything on the iPhone's retina display. If you do see an image, you are not in DFU mode.